The primary food source for the Pileated woodpecker is carpenter ants drilled from within the wood by extensive hammering and pecking. Nearly all of their foraging is done on, and in, dead trees. They drill large squarish or rectangular holes in search of prey, and in smaller trees these can weaken the trunk so much that the tree cracks off above the excavation site. In addition to trunk excavations, they will also peel off the bark and probe in search of termites and other boring insects, and will even forage on the ground in fallen logs or exposed ant hills. The force of their trunk drilling often attracts other woodpeckers and bird species. Hairy woodpeckers will follow behind Pileated woodpeckers clearing the cavities of remaining insects, as will some species of wrens.
Pileated woodpeckers are active drummers and their powerful bills and large size gives their drumming a particular resonance. Their drumming can sometimes be heard a half-mile away. They will also persist drumming for long periods of time, sometimes several hours with 60-90 second intervals in between.
This type of woodpecker mates for life and excavates new nesting sites annually. While they seem to prefer live, older trees they will also occasionally nest in utility poles. By necessity, the cavities are quite large and the opening to the nests will exceed four inches in height and 3 inches in width. Both parents participate in the excavation, which takes 3 weeks to a month to complete. These cavities, once abandoned by the Pileated, are important for dozens of other birds and animals in the forests.